Necking die assembly with internal rollers

ABSTRACT

A die assembly for forming a reduced-diameter neck on the end of a cylindrical can body having a side lap wherein no orientation of the can lap relative to the necking die is required. The can body is pushed into a ring necking die and one or more rollers roll along the inside of the can body to press the can body end outwardly against the inwardly facing reduced-diameter die surface of the necking die, the rollers being yieldable at all times away from the die so that they may roll over the can lap wherever it may be encountered.

O Unite States Patent 1191 1111 3,831,416 Wolfe Aug. 27, 1974 1 NECKING DIE ASSEMBLY WITH 2,189,004 2/1940 Harwood 72/96 INTE 2,737,996 3/1956 Toth 72/117 RNAL ROLLERS 3,688,538 9/1972 Hoyne 113/120 AA Inventor: Wayne R Wolfe, Belmont, Cahf- 3,754,424 8/1973 Costanzo 72/105 73 A U ted C C H d, Sslgnee gl an ompany aywar Primary Examiner-Charles W. Lanham Assistant Examiner-James R. Duzan [22] F1led: Jan. 4, 1973 Attorney, Agent, or FirmPhillips, Moore, [21] APPL No; 320,896 Weissenberger, Lempio & Strabala 57 ABSTRACT [52] US. Cl 72/117, 72/122, 72/124,

72/126, 113/1 G 113/7 A 37120 AA A die assembly for fornnng a reduced-d ameter neck [51] Int Cl B21 d 3/02 on the end of a cyllndncal can body havmg a side lap [58] Fieid 370 124 wherein no orientation of the can lap relative to the 72/126; 113/120 R, 120 M, 120 AA, 1 G, 7 A

necking die is required. The can body is pushed into a ring necking die and one or more rollers roll along the inside of the can body to press the can body end out- [56] References Cited wardly against the inwardly facing reduced-diameter UNITED STATES PATENTS die surface of the necking die, the rollers being yield- 234,l91 11/1880 1001' 72/117 able at all times away from the SO that they may 1,472,047 10/ 1923 Carlson... 72/124 ll over the can lap Wherever it may be encountered 1,853,641 4/1932 Seward i 72/117 2,045,235 6/1936 Newman 72/117 3 Claims, 4 Drawlng Figures 11 .2 .3 E F WX w /?5 37 II f '4 "38 2 17 19 J J' 7 ,y %j' I- .1. 4 7 1 34 Jae- W a 32 4o 30- T 35 2 6 l 3' T1 33:}

22 3'! WI/ 24 -3 H is \\\\vm 13 'II/l NECKING DIE ASSEMBLY WITH INTERNAL ROLLERS BACKGROUND OF THE INVENTION This invention relates to the formation of a reduceddiameter neck on a three-piece metal can, i.e., cans having a can body made from a rectangular piece of metal rolled into a cylinder with the edges being joined at a soldered side lap extending the length of the cylinder, the two end pieces being thereafter secured to the can body by rolling operations.

It is well known that the end of a cylindrical body can be reduced in diameter by forcing the can end into a die set comprising a ring die having an annular inwardly facing die surface of a diameter to produce the desired size neck and an inner cylindrical pilot, there being a clearance between the ring die and pilot to enable the can end to be received therebetween. It is also known that the amount of clearance between the ring and pilot is quite critical. Obviously, the clearance must be sufficient to allow the can body to be inserted therebetween. However, if the clearance is too great, then the can body end will not be properly supported during the necking operation and undesirable wrinkling of the necked portion will occur.

With deep drawn aluminum cans having no side laps, i.e., a uniform wall thickness at all points around the can end, a ring die and pilot assembly can be made easily with proper clearance. With lapped can bodies, the problem is considerably greater. A fixed ring and pilot die assembly could be made with a uniform spacing therebetween equal to the wall thickness of the can and with a larger clearance at one point therebetween to accommodate the thicker can lap. However, such a die assembly would require orientation of the can body lap to the die assembly before the can body is inserted thereinto. Such orientation is slow and expensive and unsuitable for commercial operations.

One approach to the problem of providing a can necking die assembly for lapped can bodies is that shown in U.S. Pat. No. 3,600,927 wherein a floating pilot is disposed within the ring die, with the clearance therebetween averaging half the combined thickness of the can wall and the can lap. With this arrangement, no orientation of the lap of the can body is required since the pilot can shift in any radial direction. This approach, however, requires that the lap on the can bodies be made to very close tolerances. If the lap thickness is greater than that for which the ring and pilot are designed, the can body cannot be inserted into the die set. If the lap thickness is appreciably less, then the can body end may not be suitably supported during the necking operation, and wrinkling of the can end may result.

The floating pilot approach also has an inherent drawback resulting from the fact that the ring and pilot members are both circular in cross section. At the point wherein the can lap is between the die members the gap therebetween must obviously be at least equal to the thickness of the lap. The gap between the dies gradually diminishes around the members, in either direction from the lap, with the least amount of gap, approximately the thickness of the can body wall, being at the point diametrically opposite to the can lap. As a result the gap on either side of the can lap and for a substantial distance therefrom will be only slightly less than the thickness of the lap. If the can lap is made by a process wherein the lap thickness is substantially less than twice the thickness of the can wall, the gap between the die members created by the lap will not be too detrimental. However, if the can lap is formed in a conventional manner, wherein the edges of the can body are simply lapped one over the other and soldered together, the finished lap will be in the order of three to four times the thickness of the can wall. As a consequence, if this type can body is necked with a floating pilot, the gap between the die members for a substantial distance on either side of the lap will be three times the thickness of the can wall therebetween, and the can wall will not be properly supported so as to prevent wrinkling thereof during the necking process.

SUMMARY OF THE INVENTION The present invention utilizes a ring die to reduce the diameter of the end of a can pushed thereinto. In place of a solid internal pilot, one or more rollers are mounted inside the ring die and arranged so that they will roll along the inner surface of the can body end and press the can body end outwardly against the ring die. The rollers are resiliently pressed outwardly and are free to move inwardly when the can lap is encountered.

With this arrangement, no orientation of the can body is required and substantially the entire periphery of the can end is pressed out firmly against the ring member so that undesirable wrinkling is avoided.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings forming a part of this application and in which like parts are designated by like reference numerals throughout the same,

FIG. 1 is a view, mainly in section, of a can necking machine constructed in accordance with the invention;

FIG. 2 is a view, partly in section, of the internal roller mechanism, rotated from the position shown in FIG. 1;

FIG. 3 is an end view of the internal roller mechanism of FIG. 1;

FIG. 4 illustrates the direction of movement of the internal rollers relative to the can body lap.

DESCRIPTION OF THE PREFERRED EMBODIMENT The can necking machine, generally indicated by the reference numeral 10, comprises upstanding frame members 11, a ring die holder 12 being secured by screws 13 to one of the frame members 11. A ring die 14 is mounted in die holder 12 and held in place by retainer ring 15. Die 14 has a die surface facing inwardly towards the axis of the die, the die surface comprising an annular portion 16 of a diameter substantially equal to the normal outside diameter of the can body 17, an inwardly tapering surface 18 and an annular portion 19 of reduced diameter substantially equal to the desired outer diameter of the neck to be formed on the can body. A die shoe 20 is secured in the die holder adjacent the end of the ring die 14.

Shaft 21, coaxial with the ring die, is rotatably journaled in frame members 11 by ball bearing members 22 and'23 and is provided at one end with pulley 24 which is driven by belt 25 from a suitable power source. Shaft 21 is radially enlarged at the other end to provide a support member 26 for the roller mounts 27 and 28.

Roller mount 27 is pivotally mounted at one end thereof to shaft support member 26 by screw 29, roller mount 27 having at its other end a spindle 30 the axis of which is parallel to and offset from the axis of shaft 21. Roller 31 is mounted on spindle 30, by ball bearing member 32, roller 31 having an outwardly facing annular surface 33 in opposition to the reduced-diameter surface 19 of the annular die member 14. Roller mount 28, which is a mirror image of roller mount 27, is similarly supported on shaft 21 and carries roller 34 thereon. As best shown in FIGS. 1 and 3, roller mounts 27 and 28 are provided with opposed bores 35 into which compression springs 36 are disposed, the springs acting to resiliently bias the roller mounts away from each other so that the rollers carried thereby are forced towards the die surface of the annular die member 14. As thus described, the roller mounts 27 and 28 will rotate with and by shaft 21, with the rollers being movable towards and away from the axis of shaft 21.

Adjustment screws 37 are provided to limit outward movement of roller mounts 27 and 28, the adjustment screws being locked in adjusted position by lock screws 38. Normally, the adjustment screws 37 are adjusted so that there is a clearance between rollers 31 and 34 and the die surface 19 equal to the wall thickness of the can body to be operated upon.

In operation, the shaft 21 is rotated at a desired speed, as, for example, about 2,400 rpm. A can body 17 is forced axially into the ring die 14 and first slides along the die surface portion 16 without deformation. As the end of the can is forced into engagement with and moves along the tapered die surface 18, the diameter of the end of the can will be reduced. Further movement of the can will move the can end into engagement with the rotating rollers 31 and 34 which roll along the inner edge of the can end and force such edge against the reduced-diameter die surface 19. In due course the end of the can will be forced into the ring die until it engages the die shoe 20. It is preferable to drive the shaft 21 in a direction so that the rollers 31 and 34 will move in the direction shown in FIG. 4 to minimize the bounce of the rollers as they hit the lap 40 of the can body. It has also been found preferable to time the operation so that the lap of the can is hit about times during the necking operation. Thus, with a shaft speed of 2,400 r.p.m., the cycle of can movement should be such that the end of the can is in engagement with the rollers 31 and 34 for approximately one-fourth of a second.

After the can body end has been necked as above described, the can is pulled axially from the die and the next can body is pushed thereinto.

As a roller rolls along the inner surface of the can body, the compression springs 36 force the roller outwardly so that the can end is pressed against the die portion 19. When the roller comes to the can lap 40, the springs allow the roller to yield inwardly so that it may roll past the lap, the springs forcing the roller outwardly as soon as the lap is pressed. Since the rollers may yield inwardly at any time during rotation of shaft 21 it is thus apparent that no orientation of the can body lap to the die is required.

The machine specifically illustrated and described herein utilizes two rollers wherein the axes of rotation of the rollers and shaft 21 lie in a common plane, this being a preferable construction since it provides a dynamically balanced machine with a simple spring arrangement. However, it is to be realized that only a single roller could be utilized to provide the desired necking operation. In such case, though, in order to have the single roller hit the can lap the same number of times the speed of rotation of shaft 21 would have to be doubled or the length of time of the can body in the die would have to be doubled, or a combination thereof. Also, if desired, three rollers could be mounted on shaft 21 and utilized for the necking operation. In such case, the speed of shaft 21 could be reduced or the number of cans operated upon in a given time could be increased.

Having thus described my invention, I claim:

I. Can-necking apparatus comprising:

means for inwardly deforming the end of a can body forced axially thereinto, said means including a stationary ring die having a die surface facing inwardly towards the axis of said ring die, said die surface including an annular portion of a diameter substantially equal to the diameter of the can body to be necked, an inwardly tapered surface and an annular portion of reduced diameter,

a rotatable shaft coaxial with said ring die,

a roller mount,

means mounting said roller mount on said shaft for rotation therewith and thereby and for movement of said roller mount towards and away from the axis of said shaft,

a roller carried by said roller mount for rotation about an axis parallel to and offset from the axis of said shaft, said roller having an outwardly facing cylindrical surface in opposition to said annular die surface portion of reduced diameter of said ring die and engageable by the end of a can body as said can body is forced into said ring die and said end is deformed inwardly by sliding engagement with said inwardly tapered die surface,

means resiliently pressing said roller mount away from the axis of said shaft.

2. Can-necking apparatus as set forth in claim 1 and further including:

a second roller mount,

means mounting said second roller mount on said shaft for rotation therewith and thereby and for movement of said second roller mount towards and away from said shaft,

a second roller carried by said second roller mount for rotation about an axis parallel to and offset from the axis of said shaft, said second roller having an outwardly facing cylindrical surface in opposition to said annular surface of reduced diameter of said ring die and engageable by the end of a can body as said can body is forced into said ring die and said end is deformed inwardly by sliding engagement with said inwardly tapered die surface,

means resiliently pressing said second roller mount away from the axis of said shaft.

3. Can necking apparatus as set forth in claim 2 wherein the axes of the first and second rollers and said shaft lie in a common plane. 

1. Can-necking apparatus comprising: means for inwardly deforming the end of a can body forced axially thereinto, said means including a stationary ring die having a die surface facing inwardly towards the axis of said ring die, said die surface including an annular portion of a diameter substantially equal to the diameter of the can body to be necked, an inwardly tapered surface and an annular portion of reduced diameter, a rotatable shaft coaxial with said ring die, a roller mount, means mounting said roller mount on said shaft for rotation therewith and thereby and for movement of said roller mount towards and away from the axis of said shaft, a roller carried by said roller mount for rotation about an axis parallel to and offset from the axis of said shaft, said roller having an outwardly facing cylindrical surface in opposition to said annular die surface portion of reduced diameter of said ring die and engageable by the end of a can body as said can body is forced into said ring die and said end is deformed inwardly by sliding engagement with said inwardly tapered die surface, means resiliently pressing said roller mount away from the axis of said shaft.
 2. Can-necking apparatus as set forth in claim 1 and further including: a second roller mount, means mounting said second roller mount on said shaft for rotation therewith and thereby and for movement of said second roller mount towards and away from said shaft, a second roller carried by said second roller mount for rotation about an axis parallel to and offset from the axis of said shaft, said second roller having an outwardly facing cylindrical surface in opposition to said annular surface of reduced diameter of said ring die and engageable by the end of a can body as said can body is forced into said ring die and said end is deformed inwardly by sliding engagement with said inwardly tapered die surface, means resiliently pressing said second roller mount away from the axis of said shaft.
 3. Can necking apparatus as set forth in claim 2 wherein the axes of the first and second rollers and said shaft lie in a common plane. 